1. Field of the Invention
The present invention relates to a method for detecting defects which originate from a chemical solution that is used in a semiconductor fabrication process, and a method of manufacturing a semiconductor device.
2. Description of the Related Art
In the prior art, in order to ensure the quality of a chemical solution for a resist, the chemical solution has been tested by using a particle-in-liquid counter (see, e.g. Jpn. Pat. Appln. KOKAI Publication No. 2005-300421). Thereby, particles in the chemical solution are measured on a size-by-size basis, and the quality of the chemical solution is managed on the basis of the measurement result. Specifically, the resist chemical solution is let to flow through a light-transmissive fine tube in a downward direction from above. By radiating light and observing scattered light, the presence/absence of particles is measured.
However, in the case where particles in the chemical solution are measured by the conventional method, only particles with a diameter of 0.15 μm or more can be measured at present. In other words, the number of fine particles with a diameter of, e.g. 0.05 μm to 0.15 μm, which need to be measured in actual fabrication of devices, cannot be managed.
In addition, defects, which are observed when a resist pattern is fabricated on a semiconductor substrate, do not always correspond to foreign matter which can be monitored by the particle-in-liquid counter. It is thus desirable that a defect inspection be performed by a defect inspection device after a desired resist pattern is formed on the semiconductor substrate.
However, the size of defects, which can be detected by the defect inspection device, is limited by the specifications of the inspection device. On the other hand, there is a trend that the device size will further decrease. It is thus necessary to detect a defect which occurs when a resist pattern is formed on the semiconductor substrate, and which has such a size as to affect a yield but cannot be observed by the conventional defect inspection device.